1. Field of the Invention
The present invention relates to an image pickup system having a ranging (distance measuring) function, and particularly to an image pickup system suitable for a live telecast of marathon or the like.
2. Description of the Related Art
In a telecast of marathon, measurement of runners' speeds and display thereof are required. Japanese Patent Laid-Open Nos. 5-27321 and 2007-192730 have disclosed image pickup systems that measure a moving speed of a moving object by using a ranging function which detects an object distance. Japanese Patent Laid-Open No. 2003-149256 has disclosed an image pickup system that measures a running speed of a first vehicle by using information on a running speed of a second vehicle equipped with the image pickup system and captured images of the first vehicle obtained at mutually different time points.
However, calculation of an accurate speed of the moving object in a state where the image pickup system is in movement requires detection of an absolute speed (ground speed) of the image pickup system. Further, it is necessary to calculate the absolute speed from a relative speed of the image pickup system and the moving object, the relative speed being obtained by the ranging function equipped on the image pickup system. The image pickup systems disclosed in Japanese Patent Laid-Open Nos. 5-27321 and 2007-192730 can calculate the relative speed, but cannot calculate the absolute speed.
Moreover, the image pickup system disclosed in Japanese Patent Laid-Open No. 2003-149256 needs to obtain the information on the running speed of the second vehicle equipped with the image pickup system. Thus, for example, in a telecast of marathon, absolute speeds of runners are calculated using information on the running speed of the second vehicle equipped with the image pickup system and ranging information (object distance information) obtained by the image pickup system. However, such a calculation method of the absolute speed enlarges the image pickup system.